Rock bit



June 13, 1944 w. L. CHILDS TAL ROCK BIT Filed oct. 12, lass) z sheets-sheet 1 June 13, 1944.

W. L. CHILDS EI'AL ROCK BIT Filed Oct. 12, 1939 2 Sheets-Sheet 2 William l.. Chi/:l5 John F Shaw Vl/llt')lv B. Noble g'nuenlq'Lo-- 5 J/L w/ Patented June 13, 1944 l UNITED STATESK PATENT orsi-cs aocx Brr William L. Childs. Houston, Tex., John F. Shaw.

Los Angeles, Calif., and Wiley B. Noble, Houston, Tex., assignors to Reed Boiler Bit Company, Houston, Tex., a corporation of Texas Application October 12, 1939, Serial No. 299,090

7 Claims.

This invention relates to rock bits, and more particularly to those in which the cutter assembly includes so-called cross roller cutters mounted by roller bearings and ball bearings on a transverse shaft at the forward end of the bit.

In a device of this kind, where two rotary cutters are mounted on asingle shaft between two legs depending from the bit head, nnumerous mechanical problems arise in regard to the structure oi' the shaft, roller bearing races, ball bearing races, cutters, etc., and the method of assembling the same. This is due to the fact that it is desirable to have a rigid, one-piece shaft to -provide strength and the cutters should enclose and seal the bearings as far as possible, not only for their most emcient operation but also to prevent sand, grit, etc., from entering the bearings. Further, .the ball bearing races must be smooth and uninterrupted to provide the minimum of friction and, for best results, means must be provided for inserting the balls therein without destroying the rigidity of the shaft or the surface of the cutters. We are aware thatvarious devel-,1

opments haveV71 been made in ball bearing roller bits, but, so far as we are aware, no one has deproblems in the manner of that embodied in our invention.

The primary object of our invention is to decrease the friction and increase the rigidity of vthe mountings for cross roller cutters.

. Another object is to provide an uninterrupted ball race in a cutter mounting into which the balls may be inserted without impairlng either the cutter or its shaft. f' I Another object is to provide a structure of the type' referred to which may be Areadily assembled to form adurable and elcie/nt/bit.

Further objects and features may become evident from the following disclosure, when taken in connection with the accompanying drawings, in which:

. veloped a-bearing assembly which solves the above races for roller bearings and thrust ball bearings. In the form shown in Fig. l, there are two smaller roller bearing races I4 and I4a, a thrust bearing race I6, and a larger roller bearing race I 6, on each side. In that shown in Fig. 3 there are smaller roller races I4, thrust ball bearing races I3, and larger roller bearing races I3 on each side.

In either form, the general structure of the cutter rollers is the same. This consists of a smaller bore I1, a thrust bearing race I3, and a larger bore I3. This inside conguration applies to all of the roller cutters. There is, however. in one of the rollers of each pair, an aperture 20, of a size of receive a ball bearing and spaced adjacent the ball race I8.

In its assembled position, thebit, as shown in Figs. 1 and 3, consists of the side roller cutters 20 mounted on axes downwardly and inwardly inclined with respect to the axis of the bit head. and cross roller ycutters 2| mounted on the shaft I3 by the roller bearings 22 and ball thrust bearings 23, operating in their respective races as previously described.v The threaded ends of the yshaft-I3 are securely welded to the legs II, I2,

and these legs are welded to the head I0. A bridge 24, whose specific structure will be hereinafter described, is utilized to keep the roller cutters separated and in position, and to serve as a support for the inner ends of the side cutter shafts and the central portion of the cross cutter shaft.

The assembling of the device is performed as follows: First the shaft I3 is screwed into the leg II. Then the roller bearings I4, I4a, 22 and the thrust bearings 23 are placed, in heavy grease to hold them in position, in their respective races on the side of the shaft toward the leg II. A roller cutter is then slipped on, and it fits into place with its race I3 engaging the balls 23. Then the smaller roller bearings I4, I4a are tted into place on the other side of the shaft. and

Fig. 1 is a lonigtudinalcross section of a drill Fig. 3 is a longitudinal cross-section of a.`

slightly dierent drill bit embodying my invention; and

Fig. 4 is a fragmentary cross-section taken along the line 4-4 of Fig. 3.

Referring to the drawings in detail, a bit body I0 has depending therefrom and welded thereto the legs II, I2 carrying screw-threadedbetween them the shaft I3.

the other roller cutter is slipped on, beyond its normal position, so that the aperture 20 is opposite the ball `race I5. Ball bearings are then inserted through the aperture 20 until the race I5 is full. While the cutter is in this position its larger roller bearings 22 are inserted and then the cutter is moved toward its end of the shaft,

until its race I3 engages the ball bearings. 'I'his moves aperture 20 out of the way, to leave a smooth, uninterrupted race. The bridge 24 is then-.inserted to space the two cutters, and the 'other leg I2 is screwed on. Both legs are welded Shaft I3 is formed with 55 to the bit head I0 and the shaft I3 is welded to the legsY at its threaded portions, to produce rigidity. The aperture 2l may be welded closed to prevent the entry of dirt to the bearings.

The bridge 24 extends between the adjacent ends of the side cutter shafts and is formed with a notched portion 2i which ilts over the shaft I3. A segment 26 o r 26' iswelded into place in the bottom of the notch, and in the form shown in Fig. 2, this segment 20 has a nose 21 which acts on the center oi the hole to prevent the formation of a core.

It will be seen that by our structure and method of assembling the same we produce a smoothoperating, compact and rigid bit having cross roller cutters. We do not wish to be limited to the specific embodiments of the invention set out herein, but only by the' scope of the appended claims.

We claim:

1. In a cross roller bit. a body, depending legs on said body, a continuous lshaft mounted between said legs, cross roller cutters on the shaft. thrust ball bearings between each of said cutters and said shaft. said thrust bearings being oppositely disposed to each other to take outward thrust from said cutters, and uninterrupted inwardly facing raceways for said bearings on said continuous shaft.

2. In a cross roller bit, a body, depending legs on said body, a continuous shaft mounted between said legs and having ball and roller bearing raceWayS, cross roller cutterson the shaft, roller bearings for taking the radial load on said cutters and thrust ball bearings between the shaft and said cutters to take outward thrust from said cutters, said thrust bearings being oppositely disposed to each other, and uninterrupted raceways for said thrust bearings.

3. In a cross roller bit, a body, depending legs l on said body, a continuous shaft mounted between said legs, cross roller cutters upon said shaft, va bridge extending between said cutters and spacing them from each other, ball thrust bearings between each cutter and said shaft, said bearings being oppositely disposed to take outward thrust from said cutters and uninterrupted inwardly facing raceways for said bearings on said continuous shaft.

4. In a cross roller bit, a body. depending legs on said body, a continuous shaft mounted between said legs and having ball and roller bearing raceways, two roller cutters upon said shaft, radial roller bearings and ball thrust bearings between each of said cutters and said shaft, said l ball thrust bearings being oppositel'y disposed to take outward thrust from said cutters, and a bridgeiextending'between said cutters and spacing them from each other, said ball thrust bearings having uninterrupted raceways.

5. In a cross roller bit, a body, depending legs on'said body, a continuous shaft mounted between said legs, two roller cutters on said shaft, radial bearings and ball thrust bearings between each of said cutters and said shaft, a bridge extending between said cutters and spacing them from each other, said thrust bearings being oppositely disposed to take outward thrust from said cutters and having uninterrupted raceways, and a forwardly extending bit on said bridge adapted to cut the center of a bore hole and prevent the formation of a core in the operation of said bit.

6. In a, cross roller bit, a body, depending legs on said body, a continuous shaft mounted be- -for said ball thrust bearings in said cutter.

7. In a roller bit assembly, a bit head, two depending legs, a shaft between said legs, said shaft having two roller bearing races at its ends. two thrust ball bearing races adjacent thereto, two central roller bearing races adjacent the ball races, a rst roller cutter mounted thereon having an enlarged bore toward the end of the shaft, a smaller bore toward the center of the shaft, a thrust ball race between the two, large roller bearings in the enlarged bore, balls in the bail race, smaller roller bearings in the small bore. a spacing bridge, a roller cutter having a small bore adjacent the bridge, small rollers in this bore, a ball race, ball bearings in the race, a large bore toward the end of the shaft, 'large roller bearings in the bore, said last-mentioned cutter having a hole through its side spaced from the ball race a distance of less than the spacing bridge and of a size to receive ball bearings, and a cutting nose on said spacing means.

WILLIAM L. CHILDS. JOHN F. SHAW. WILEY B. NOBLE. 

